Solve for x the equation
`|(a^(2),a,1),(sin(n+1)x,sin nx,sin(n-1)x),(cos(n+1)x,cosn x,cos(n-1)x)|=0`

Explanation

To solve the equation

\[
\left|
\begin{array}{ccc}
a^2 & a & 1 \\
\sin((n+1)x) & \sin(nx) & \sin((n-1)x) \\
\cos((n+1)x) & \cos(nx) & \cos((n-1)x)
...